1. Field of the Invention
This invention relates to the protection of integrated circuit (IC) devices against latch-up during a nuclear event.
2. Description of the Related Art
Latch-up occurs in an IC device when a transient gamma pulse arising at a nuclear event causes parasitic components within the device to become locked in a permanent state. This renders the IC device useless and may lead to its burn out.
A conventional method of preventing such latch-up is to arrange for the power supply of an equipment incorporating IC devices susceptible to such latch-up to be temporarily grounded via a so-called crow-bar switch which is closed in response to detection of a nuclear event by a detector specifically provided for the detection of such events.
Such a method has the disadvantages that the crow-bar switch has to become very rapidly capable of passing a large current and that the supply is interrupted not only to IC devices which require gamma induced latch-up protection, but also to other devices of an equipment.